Bioavailability of Phytoestrogens and Prevalence of Adenomatous Polyps in Human Colon

INTRODUCTION: The data obtained by experimental studies about the influence of phytoestrogens on colorectal cancer (CRC) have been very promising. On the other hand, clinical trials have produced conflicting results. The literature suggests that some subclasses of phytoestrogens may have protective effects against CRC and colon adenomas, but most of these results come from population studies based on the dietary intake of phytoestrogens. On these premises, it is possible to hypothesize that the variability of the data reported in the literature may be due to the fact that the real absorption of phytoestrogens (by assessing their concentration in the serum or urine) and/or the ability of the single individual of producing equol was not evaluated.

PURPOSE: In the present study, the association between the phytoestrogens intake and the prevalence of colon adenomas was evaluated not only on the basis of the simply dietary intake but also on the measurement their intestinal absorption. Moreover, a specific evaluation of equol production by the intestinal flora was performed. Finally, intestinal bacteria involved in equol production were evaluated.